Indiana's corn is showing potential to produce a bumper crop for the second consecutive year, but much of it could "suffer quickly" if growing conditions turn unfavorable, Purdue Extension corn specialist Bob Nielsen says.

He is cautiously optimistic as the crop enters the second half of the growing season toward harvest.

"Yes, the corn crop in Indiana looks good at this point in time. Yes, the prospects for good yields this year are promising," he wrote Tuesday (July 15) in his online Chat 'n Chew Café. Likening the growing season to baseball, he added: "But the crop has only 'rounded second base' on its way to 'home plate.'"

Seventy-five percent of Indiana's corn crop was in good or excellent condition as of the week ending July 13, compared with 80 percent a year ago, according to the U.S. Department of Agriculture's National Agricultural Statistics Service. Nationally, 76 percent of the crop had that rating as of last week.

Last year, Indiana farmers produced a record 1.03 billion bushels of corn. A bountiful crop two years in a row would be a marked contrast to 2012, when extreme, widespread drought exacted a heavy toll on crops and Indiana farmers produced only 597 million bushels of corn.

The upside for some of the 2014 corn crop, Nielson said, is that stand establishment was good, there has been no shortage of rainfall to date for most fields, temperatures have been moderate, there have been few incidents of plant disease and the weather forecast for much of the pollination period this month looks favorable.

The downside, he explained, is that planting was delayed for some farmers because of frequent spring rain, stand establishment was "terrible" in some fields, requiring at least one replanting, and subsequent, excessive rainfall caused root death or damage, plant mortality, overall stunting of the crop and significant loss of soil nitrate-nitrogen.

"If Mother Nature's 'spigot' would turn off and soils rapidly dry to excessively low levels, much of this crop that is likely shallow-rooted due to the early wet season would suffer quickly," Nielsen said.

Conditions have been conducive recently for development of foliar diseases. "But time will tell whether they will explode or not over the coming weeks," he said.

Nielsen also said it was curious that excessive rain in many areas has not resulted in widespread symptoms of nitrogen deficiency. The question of whether nitrogen deficiency may yet appear during the grain fill period and limit kernel weight lingers.

"Any severe stress during the grain fill period that limits photosynthesis will encourage corn plants to remobilize stored carbohydrates from the lower stalk tissue to the developing kernels," he said.

Such "cannibalization" of lower stalk tissue could lead to root or stalk rot disease, leading to weaker stalks and higher risks of stalk breaking or lodging - falling over - before harvest. Such severe photosynthetic stresses include foliar disease, nutrient deficiency, hail damage and drought stress.

Weather patterns over the next few weeks are not expected to change much, aside from the unseasonably cool temperatures this week, said Dev Niyogi, state climatologist based at Purdue.

"For our region, the persistence of wetter and warm conditions will likely continue," Niyogi said. "There is nothing on the horizon to expect massive, large-scale changes."

But there will be increased likelihood of thunderstorms, with heavy downpours, especially as tropical systems become active, he said. "The atmosphere looks primed for that."

The climate office also said an El Nińo weather pattern bringing slightly cooler-than-normal temperatures and seasonally normal to slightly wetter-than-normal conditions could arrive in mid- to late August.

Nielsen's Chat 'n Chew Café can be accessed at http://www.agry.purdue.edu/ext/corn/cafe/.